JP2005330469A - Dye and dye-sensitized solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new dye capable of exhibiting high conversion efficiency and excellent weather resistance and heat resistance, when used for a dye-sensitized solar cell, and to provide the dye-sensitized solar cell given by using the dye. <P>SOLUTION: This dye is expressed by formula (1): ML<SP>1</SP>L<SP>2</SP>X<SP>1</SP>X<SP>2</SP>(M is a group 8, 9 or 10 element on the long periodic table; L<SP>1</SP>and L<SP>2</SP>are each a bidentate ligand comprising a specified bipyridine; and X<SP>1</SP>and X<SP>2</SP>are each a monovalent atomic group or a monodentate ligand). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dye and a dye-sensitized solar cell using the same.

  With increasing interest in energy problems, research on solar cells that can efficiently convert light, particularly sunlight, into electricity is underway. As solar cells, silicon-based solar cells using amorphous silicon or polycrystalline silicon have begun to spread. However, silicon-based solar cells are high in cost and have problems in terms of supplying high-purity silicon, and are generally said to be limited in widespread use.

In recent years, dye-sensitized solar cells have attracted attention. Dye-sensitized solar cells have high power generation efficiency, relatively low manufacturing costs, inexpensive oxide semiconductors such as titanium oxide can be used as raw materials without being purified to high purity, and equipment used for manufacturing is inexpensive Therefore, it is expected to have many advantages over silicon-based solar cells (see Patent Document 1 and Patent Document 2).
In dye-sensitized solar cells, it is known that power generation efficiency, weather resistance, and heat resistance greatly depend on the dye.
As a conventionally known dye, a dye called “N719” represented by the following formula (4) and a dye called “black dye” represented by the following formula (5) are widely used (non- (See Patent Document 1 and Non-Patent Document 2).

In formulas (4) and (5), TBA ⁺ represents a tetrabutylammonium ion.
However, these dyes are excellent in quantum yield, but are not sufficient in terms of conversion efficiency, weather resistance, heat resistance and the like as solar cells, and development of further excellent dyes is awaited.
US Pat. No. 4,927,721 International Publication No. 98/50393 Pamphlet J. et al. Am. Chem. Soc. 115, 6382-6390 (1993) J. et al. Am. Chem. Soc. , 123, 1613-1624 (2001)

  The present invention has been made in view of the above circumstances, and its purpose is to use a novel dye exhibiting high conversion efficiency, excellent weather resistance, and heat resistance when used in a dye-sensitized solar cell, and the dye. The object is to provide a dye-sensitized solar cell.

  Still other objects and advantages of the present invention will become apparent from the following description.

According to the present invention, the above objects and advantages of the present invention are as follows.
This is achieved by a dye represented by the following formula (1).
ML ¹ L ² X ¹ X ² (1)
Here, M is a group 8 to 10 element on the long periodic table, and L ¹ and L ² are each independently a bidentate ligand represented by the following formulas (2) and (3): And X ¹ and X ² are each independently a monovalent atomic group or a monodentate ligand.

In the formula (2), A ¹ is a carboxyl group, a sulfonic acid group or a phosphoric acid group or a group corresponding to a salt thereof, R, R ¹ and R ² are each independently a monovalent organic group, and m1 and m2 each independently represent an integer of 0 to 3.

In the formula (3), A ² and A ³ are each independently a group corresponding to a carboxyl group, a sulfonic acid group or a phosphoric acid group or a salt thereof, and R ³ and R ⁴ are each independently a monovalent group. An organic group and m3 and m4 each independently represents an integer of 0 to 3. However, when both L ¹ and L ² are bidentate ligands represented by the formula (3), A ² and A ³ are not both a carboxyl group or a group corresponding to a salt thereof. .

According to the present invention, the above objects and advantages of the invention are secondly,
This is achieved by a dye-sensitized solar cell using the above dye.

The coloring matter of the present invention is represented by the above formula (1). In the formula (1), M is an element of group 8 to 10 on the long periodic table, and L ¹ and L ² are each independently a bidentate represented by each of the above formulas (2) and (3) Any of the ligands, and X ¹ and X ² are, independently of one another, a monovalent atomic group or a monodentate ligand.
In the formula (2), A ¹ is a carboxyl group, a sulfonic acid group or a phosphoric acid group or a group corresponding to a salt thereof, and R, R ¹ and R ² are independently a monovalent organic group. , And m1 and m2 each independently represents an integer of 0 to 3.
Further, in the formula (3), A ² and A ³ are each independently a group corresponding to a carboxyl group, a sulfonic acid group or a phosphoric acid group or a salt thereof, and R ³ and R ⁴ are each independently one another. And m3 and m4 each independently represents an integer of 0 to 3.

  Examples of M include group 8 iron, ruthenium, osmium, group 9 cobalt, rhodium, iridium, and group 10 nickel, palladium, and platinum. Of these, ruthenium is particularly preferred.

A ¹ in formula (2) and A ² and A ^{3 in} formula (3) are each independently a group corresponding to a carboxyl group, a sulfonic acid group or a phosphoric acid group or a salt thereof. Of these, a group corresponding to a carboxyl group or a salt thereof is preferable.

When A ¹ , A ² or A ³ is a group corresponding to a salt, examples of the counter cation include ammonium ion, dimethyl ammonium ion, diethyl ammonium ion, tetramethyl ammonium ion, tetraethyl ammonium ion, tetrapropyl ammonium ion, tetra A butylammonium ion, a sodium ion, a potassium ion etc. can be mentioned.
Moreover, as a monovalent organic group of R in Formula (2), the organic group represented, for example by following formula (6)-(9) can be mentioned as a preferable thing.

In the above formulas (6) to (9), R ^{5 to} R ⁹ are each independently an alkyl group having 1 to 50 carbon atoms or the following formula (10)

Here, R ¹⁰ is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, m5 is an integer of 0 to 20, and m6 is an integer of 1 to 20.
It is group represented by these. When R ^{5 to} R ⁹ are an alkyl group having 1 to 50 carbon atoms, the alkyl group may be linear or branched.
The group represented by the above formula (7) is preferably an alkylaminocarbonyl group having 3 to 50 carbon atoms.
As the monovalent organic group of ^{R 3} and ^{R 4} of ^R 1, ^{R 2} and the formula in the formula (2) (3), for example, include an alkyl group or an alkoxyl group having 1 to 4 carbon atoms be able to.
Furthermore, examples of the monovalent atomic group or monodentate ligand of X ¹ and X ^{2 in} the above formula (1) include atomic groups or ligands represented by the following formulas (11) to (17). be able to.

In the above formula (12), R ¹¹ is an alkyl group having 1 to 6 carbon atoms. In the formulas (13) and (17), Ar represents an aryl group having 6 to 12 carbon atoms.
Of these, X ¹ and X ² are preferably isothiocyanates represented by the above formula (11).
Such a dye of the present invention can be suitably used for a dye-sensitized solar cell.

  The dye-sensitized solar cell of the present invention using the dye of the present invention has at least a cathode, an anode facing the cathode, and an electrolyte held between the cathode and the anode. The cathode has an oxide thin film electrode on which a dye of the present invention is chemisorbed on a transparent conductive glass. Here, as the transparent conductive glass, for example, tin oxide, indium-tin oxide (ITO), or the like can be used.

  Examples of the material constituting the oxide thin film electrode include titanium oxide, niobium oxide, zinc oxide, tin oxide, tungsten oxide, and indium oxide. Of these, titanium oxide, niobium oxide, and tin oxide are preferable, and titanium oxide is particularly preferable. There is no limitation on the method of forming the oxide thin film electrode. For example, oxide fine particles to be an oxide thin film electrode are formed, suspended in an appropriate solvent, applied onto transparent conductive glass, and the solvent is added. After removal, it can be advantageously produced by a heating method.

  In order to adsorb the dye of the present invention to the oxide thin film electrode, an appropriate method can be adopted. For example, the transparent conductive glass having an oxide thin film electrode on the surface obtained as described above can be immersed in a solution containing the dye of the present invention. Examples of the solvent that can be used here include diethyl ether, acetonitrile, ethanol, and the like. The concentration of the dye solution is preferably 0.1 to 10 mmol / L. As immersion time, 0.5 to 100 hours are preferable, and 2 to 50 hours are more preferable. As temperature at the time of immersion, it is preferable that it is 0-100 degreeC, and it is more preferable that it is 10-50 degreeC.

Although there is no restriction | limiting in particular as long as it has electroconductivity, For example, what attached a trace amount platinum or electroconductive carbon on transparent conductive glass can be used suitably.
As the electrolyte, for example, a solution containing a redox system, a solid, or an ionic liquid can be used. Specific examples thereof include, for example, the following reaction of iodine as a redox system.

I ₃ ⁻ + 2e ⁻ = 3I ⁻ + I ₂

And an electrolyte solution containing, for example, acetonitrile, propionitrile, or the like as a solvent.
As described above, according to the present invention, when used in a dye-sensitized solar cell, a novel dye exhibiting high conversion efficiency, excellent weather resistance, and heat resistance is provided. Moreover, the dye-sensitized solar cell of the present invention using the above dye has high conversion efficiency and excellent weather resistance and heat resistance.

  Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1
Synthesis of Ligand 40 g of 4,4′-dimethyl-2,2′-bipyridine was added in small portions with stirring to 1 L of 98 wt% concentrated sulfuric acid and dissolved. Next, 55 g of potassium dichromate was added to this solution little by little while keeping the solution temperature at 65 ° C. or lower. The reaction mixture was allowed to cool to room temperature (23 ° C.) and then poured into 12 L of ice water with stirring. Stirring was continued for 2 hours, and then the precipitate was collected by filtration and washed with water. The resulting solid was redissolved in ether, purified by passing through a silica gel column, and the solvent was removed to give 3.8 g of product. This product was analyzed by ¹ H-NMR and found to be 4-carboxy-4′-methyl-2,2′-bipyridine.

Synthesis of Dye 4-Carboxy-4′-methyl-2 synthesized above was dissolved in a solution of 0.3 g of (p-cymene) ruthenium (II) dichloride dimer in 150 mL of N, N-dimethylformamide. , 2'-bipyridine 0.205g was added. The mixture was stirred at 60 ° C. for 4 hours under a nitrogen atmosphere, 0.234 g of 4,4′-dicarbonyl-2,2′-bipyridine was added, and the mixture was refluxed for 4 hours. Thereafter, 3.5 g of potassium isothiocyanate was added, and the reflux was further continued for 4 hours.

The reaction mixture was allowed to cool to room temperature (23 ° C.), N, N-dimethylformamide was removed under reduced pressure, and 550 mL of water was added. Further, while stirring at room temperature, dilute nitric acid was added to adjust the pH to 2.5, and then the precipitate was collected by filtration. This solid was redissolved in methanol and purified by passing through a Sephadex LH-20 column (commercially available, manufactured by Amersham Biosciences) to obtain 0.12 g of product. ^When analyzed by ¹ H-NMR, it was found that this product was represented by the following formula (18). This product is referred to as “J1”.

Manufacture of dye-sensitized solar cell In a mixed medium of 0.4 mL of acetylacetone and 20 mL of ion-exchanged water, 12 g of titanium oxide fine particles and 0.2 g of a dispersant Triton X-100 (commercial product, manufactured by Aldrich) are added, and the dispersion Was prepared. This dispersion is applied onto a 1 mm thick conductive glass substrate (made of tin oxide, resistance value = 10 Ω / cm ² ), heated in air at 500 ° C. for 1 hour, and a conductive film having a titanium oxide thin film on the surface. Glass substrate was obtained. The glass substrate was immersed in an ethanol solution containing the dye “J1” synthesized above at a concentration of 0.2 mmol / L for 24 hours at room temperature to chemisorb the dye of the present invention onto the transparent conductive glass. A cathode having an oxide thin film electrode was produced.

On the other hand, platinum was vapor-deposited on another conductive glass substrate (thickness 1 mm, made of tin oxide, resistance value = 10 Ω / cm ² ) to produce an anode.
Furthermore, an electrolyte solution containing 0.1 mol / L iodine and 0.5 mol / L lithium iodide in acetonitrile was prepared.
A dye-sensitized solar cell having a structure in which the cathode and the anode were opposed to each other and the electrolyte solution was sandwiched therebetween was manufactured.

Evaluation of Dye-Sensitized Solar Cell For the dye-sensitized solar cell manufactured as described above, pseudo-sunlight with an illuminance of 1,000 W / m ² using a solar simulator “WXS-50S-1.5” (manufactured by WACOM) And the initial photoelectric conversion efficiency was measured and found to be 6.5%. Thereafter, irradiation with pseudo-sunlight was continued, and the time until the photoelectric conversion efficiency became one-half of the initial value was measured as a half-time, and was 1200 hours.

Example 2
Synthesis of Ligand 100 mL of tetrahydrofuran was added to 11 mL of a tetrahydrofuran solution of 2 mol / L lithium diisopropylamide and cooled to -70 ° C. While stirring the solution at −70 ° C., 2.0 g of 4-carboxy-4′-methyl-2,2′-bipyridine powder synthesized in the “ligand synthesis” step of Example 1 was slowly added. . Stirring was then continued for 1 hour at −10 ° C., and then 100 mL of a tetrahydrofuran solution containing 5.5 g of dodecyl bromide was added dropwise at −10 ° C. The reaction mixture was warmed to room temperature and stirred for another hour.

Thereafter, 250 mL of ice water was added, and the pH was adjusted to 2.0 with concentrated hydrochloric acid. The aqueous layer was extracted with ether, concentrated and dried, then purified by passing through a silica gel column, and the solvent was removed to obtain 1.1 g of product. This product was analyzed by ¹ H-NMR and found to be 4-carboxy-4′-tridecyl-2,2′-bipyridine.

Dye Synthesis In Example 1, “Dye Synthesis”, instead of 0.205 g of 4-carboxy-4′-methyl-2,2′-bipyridine, 4-carboxy-4′-tridecyl-synthesized above was used. This was carried out in the same manner as in Example 1 except that 0.38 g of 2,2′-bipyridine was used, and 0.18 g of a product was obtained. Analysis by ¹ H-NMR revealed that the product was represented by the following formula (19). This product is referred to as “J2”.

Production of dye-sensitized solar cell, evaluation In "Production of dye-sensitized solar cell" in Example 1, except that the dye "J2" was used instead of the dye "J1", the same as in Example 1, A dye-sensitized solar cell was produced and evaluated in the same manner as in “Evaluation of dye-sensitized solar cell” in Example 1. The results are shown in Table 1.

Example 3
Synthesis of the ligand 30 g of 4,4′-dicarboxy-2,2′-bipyridine and 500 g of thionyl chloride were refluxed for 3 hours. After removing unreacted thionyl chloride, 500 mL of methylene chloride, 17 g of diethylamine and 1.5 g of 4-dimethylaminopyridine were added and stirring was continued at room temperature for 24 hours. The reaction mixture was then washed with dilute hydrochloric acid and purified by a silica gel column, and the solvent was removed to obtain 5.6 g of product. When this product was analyzed by ¹ H-NMR, it was found to be 4-carboxy-4′-N, N-diethylaminocarbonyl-2,2′-bipyridine.

Dye Synthesis In Example 1, “Dye Synthesis”, instead of 0.205 g of 4-carboxy-4′-methyl-2,2′-bipyridine, the 4-carboxy-4′-N, synthesized above was used. This was carried out in the same manner as in Example 1 except that 0.287 g of N-diethylaminocarbonyl-2,2′-bipyridine was used, and 0.15 g of a product was obtained. ^When analyzed by ¹ H-NMR, it was found that this product was represented by the following formula (20). This product is referred to as “J3”.

Production of dye-sensitized solar cell, evaluation In "Production of dye-sensitized solar cell" in Example 1, except that the dye "J3" was used instead of the dye "J1", the same as in Example 1, A dye-sensitized solar cell was produced and evaluated in the same manner as in “Evaluation of dye-sensitized solar cell” in Example 1. The results are shown in Table 1.

Example 4
Synthesis of Ligand In Example 3 “Synthesis of Ligand”, 46 g of N-methyl-N-dodecylamine was used instead of 17 g of diethylamine. Performed substantially as in “Synthesis” to give 3.2 g of product. This product was analyzed by ¹ H-NMR and found to be 4-carboxy-4′-N-methyl-N-dodecylaminocarbonyl-2,2′-bipyridine.

Dye synthesis In Example 1, “Dye synthesis”, instead of 0.205 g of 4-carboxy-4′-methyl-2,2′-bipyridine, 4-carboxy-4′-N— synthesized above was used. The procedure of Example 1 was repeated except that 0.408 g of methyl-N-dodecylaminocarbonyl-2,2′-bipyridine was used, and 0.21 g of product was obtained. ^When analyzed by ¹ H-NMR, it was found that this product was represented by the following formula (21). This product is referred to as “J4”.

Production of dye-sensitized solar cell, evaluation In "Production of dye-sensitized solar cell" in Example 1, except that the dye "J4" was used instead of the dye "J1", the same as in Example 1, A dye-sensitized solar cell was produced and evaluated in the same manner as in “Evaluation of dye-sensitized solar cell” in Example 1. The results are shown in Table 1.
Comparative Example 1

Manufacture of dye-sensitized solar cell and evaluation "Manufacture of dye-sensitized solar cell" in Example 1 Commercially available dye "N3" (manufactured by Solaronix Co., Ltd., in the above formula (4) instead of dye "J1") In the structure shown, a dye-sensitized solar cell was manufactured in substantially the same manner as in Example 1 except that a dye having a structure in which both tetrabutylammonium ions were replaced with hydrogen ions. Evaluation was performed in the same manner as in “Evaluation of dye-sensitized solar cell” in Example 1. The results are shown in Table 1.

Example 5
In a ligand synthesis vessel, 6.39 g of 4,4′-dimethyl-2,2′-bipyridine, 4.16 g of selenium dioxide and 375 mL of 1,4-dioxane (386.4 g) were charged and refluxed for 24 hours. Then, hot filtration was performed. After the filtrate was concentrated, 225 mL of ethanol and an aqueous silver nitrate solution (6.48 g / 50 mL) were added thereto, and 100 mL of a 1.5 mol / L aqueous sodium hydroxide solution was further added. The solution was stirred at room temperature for 15 hours. Next, the solution was filtered, and after ethanol was removed under reduced pressure, the solution was washed with 150 mL of chloroform. When a mixed solution of acetic acid and 4N normal hydrochloric acid in a volume ratio of 1: 1 was added to the washed solution to adjust the pH to 3.5, a white solid was precipitated. The mixture was allowed to stand at 10 ° C. for one day, and the solid was filtered off and dried. The solid was solid-liquid extracted with isopropyl alcohol, and the solvent was removed under reduced pressure to give 2.26 g of product. When this was analyzed by ¹ H-NMR, it was found to be 4-carboxy-4′-methyl-2,2′-bipyridine.
¹ H-NMR (DMSO-d6, 298K, 270 MHz, δ (ppm)); δ = 8.86 (d, 1H), 8.82 (s, 1H), 8.58 (d, 1H), 8. 27 (s, 1H), 7.86 (s, 1H), 7.33 (d, 1H), 2.44 (s, 3H, Me)

Synthesis of dye After degassing under reduced pressure, 25 mg of anhydrous N, N-dimethylformaluminide in a nitrogen atmosphere, 50 mg of ruthenium (II) dichloride (p-cymene) ruthenium (II) and 4,4′-dicarboxy-2,2 dried under reduced pressure 39.08 mg of '-bipyridine was added and placed under a nitrogen stream for 10 minutes. Under a nitrogen atmosphere, this solution was stirred at 60 ° C. for 4 hours, and then 34.28 mg of 4-carboxy-4′-methyl-2,2′-bipyridine (synthesized above) dried under reduced pressure was added, It was placed in a nitrogen stream for 10 minutes. Subsequently, this solution was stirred at 150 ° C. for 4 hours under a nitrogen atmosphere, allowed to cool to 100 ° C., and then added with 155.49 mg of potassium isothiocyanate dissolved in 2.5 mL of ion-exchanged water. For 4 hours. The reaction mixture was allowed to cool to room temperature, the solvent was removed under reduced pressure, and 0.87 wt% aqueous sodium carbonate solution was added. Further, while stirring at room temperature, 0.5N normal nitric acid was added dropwise little by little to adjust the pH to 3.0, and a precipitate was found. This was left to stand overnight, and then centrifuged to recover a solid. The collected solid was washed three times with a small amount of ion-exchanged water and then lyophilized. This solid was dissolved in a small amount of N, N-dimethylformamide and purified by column chromatography using Sephadex LH-20 (commercial product, manufactured by Amersham Biosciences) to obtain 60 mg of product. This was analyzed by ¹ H-NMR and found to be represented by the above formula (18).
¹ H-NMR (DMSO-d6, 298K, 270 MHz, δ (ppm)); δ = 9.41 (m), [9.11-8.74 (m), 8.33 (m), 7.77 -7.10 (m); COH], 2.42 (s, 3H)
The purification using a Sephadex LH-20 column was performed according to the following procedure.

  A commercially available Sephadex LH-20 gel was immersed overnight to swell and then packed into a column (3 × 60 cm). After 400 mL of N, N-dimethylformamide was passed through this column, 300 mL of a 0.1 wt% N, N-dimethylformamide solution of lithium chloride was passed. The entire amount of the crude dye product was dissolved in 5 mL of N, N-dimethylformamide and loaded onto the column, and the dye was eluted with 0.1% by weight of a solution of lithium chloride in N, N-dimethylformamide. The eluted dye was recovered, the solvent was removed under reduced pressure, lithium chloride was removed by washing with water, the dye was recovered by centrifugation, and then dried under reduced pressure to obtain a purified dye.

Production and Evaluation of Dye-Sensitized Solar Cell Titanium oxide paste Ti-Nanoxide D / SP (average particle diameter of titanium oxide 13 nm) manufactured by Solaronix Co., Ltd. was applied to a 1.1 mm-thick conductive glass substrate (ITO (indium-tin on the surface). -Oxide) It was applied on a glass substrate having a thin film, resistivity 10 Ω / cm ² ) and heated in air at 500 ° C. for 30 minutes. The glass substrate after this treatment was immersed in an aqueous solution containing the dye obtained above at a concentration of 0.2 mmol / L for 12 hours at room temperature, and then allowed to stand at 23 ° C. for 1 hour to dry. A glass substrate having an adsorbed titanium oxide layer was obtained.

Separately, platinum was sputtered on a conductive glass substrate (resistivity 10 Ω / cm ² ) to prepare a counter electrode.
Acetonitrile containing the two types of glass substrates produced above facing each other at a distance of 100 μm with the titanium oxide layer and the platinum layer inside, respectively, and 0.1 mol / L iodine and 1.5 mol / L lithium iodide in between. The solution was charged to produce a dye-sensitized solar cell.

This dye-sensitized solar cell is irradiated with pseudo-sunlight (1,000 W / m ² ) from the side of the glass substrate having the titanium oxide layer by using an artificial solar illumination lamp XC-100A (manufactured by Biot), and photoelectric conversion is performed. When the efficiency was measured, the conversion efficiency was 5.6%. Thereafter, irradiation with pseudo-sunlight was continued, and the time from immediately after the start of startup until the value of this conversion efficiency was ½ of the initial value was measured as a half-time, which was 967 hours.

Comparative Example 2
In Example 5, a dye-sensitized solar cell was produced and evaluated in the same manner as in Example 5 except that N3 dye was used as the dye. The change rate was 4.8% and the half-life was 767 hours.

Example 6
Synthesis of Ligand 40 g of 4,4′-dimethyl-2,2′-bipyridine was added in small portions with stirring to 1 L of 98 wt% concentrated sulfuric acid and dissolved. Next, 55 g of potassium dichromate was added to this solution little by little while keeping the solution temperature at 65 ° C. or lower. The reaction mixture was allowed to cool to room temperature (23 ° C.) and then poured into 12 L of ice water with stirring. Stirring was continued for 2 hours, and then the precipitate was collected by filtration and washed with water. The resulting solid was redissolved in ether, purified by passing through a silica gel column, and the solvent was removed to give 3.8 g of product. This product was analyzed by ¹ H-NMR and found to be 4-carboxy-4′-methyl-2,2′-bipyridine.

Synthesis of Dye 4-carboxy-4′-methyl-2,2′-bipyridine synthesized above was added to a solution of 0.71 mmol of Ru (dimethyl sulfoxide) ₄ Cl ₂ dissolved in 30 mL of N, N-dimethylformamide. .42 mmol was added. After the mixture was refluxed for 4 hours, 2.8 g of potassium isothiocyanate was added and reflux was continued for an additional 4 hours.

The reaction mixture was allowed to cool to room temperature (23 ° C.), N, N-dimethylformamide was removed under reduced pressure, and 600 mL of water was added. Further, while stirring at room temperature, dilute nitric acid was added to adjust the pH to 2.5, and then the precipitate was collected by filtration. This solid was redissolved in methanol and purified by passing through a Sephadex LH-20 column (commercially available, manufactured by Amersham Biosciences) to obtain 0.34 g of product. ^When analyzed by ¹ H-NMR, it was found that this product was represented by the following formula (22). This product is referred to as “S1”.

Manufacture of dye-sensitized solar cell In a mixed medium of 0.4 mL of acetylacetone and 20 mL of ion-exchanged water, 12 g of titanium oxide fine particles and 0.2 g of a dispersant Triton X-100 (commercial product, manufactured by Aldrich) are added, and the dispersion Was prepared. This dispersion is applied onto a 1 mm thick conductive glass substrate (made of tin oxide, resistance value = 10 Ω / cm ² ), heated in air at 500 ° C. for 1 hour, and a conductive film having a titanium oxide thin film on the surface. Glass substrate was obtained. The glass substrate was immersed in an ethanol solution containing the dye “S1” synthesized above at a concentration of 0.2 mmol / L for 24 hours at room temperature to chemisorb the dye of the present invention onto the transparent conductive glass. A cathode having an oxide thin film electrode was produced.

On the other hand, platinum was vapor-deposited on another conductive glass substrate (thickness 1 mm, made of tin oxide, resistance value = 10 Ω / cm ² ) to produce an anode.
Furthermore, an electrolyte solution containing 0.1 mol / L iodine and 0.5 mol / L lithium iodide in acetonitrile was prepared.
A dye-sensitized solar cell having a structure in which the cathode and the anode were opposed to each other and the electrolyte solution was sandwiched therebetween was manufactured.

Evaluation of Dye-Sensitized Solar Cell For the dye-sensitized solar cell manufactured as described above, pseudo-sunlight with an illuminance of 1,000 W / m ² using a solar simulator “WXS-50S-1.5” (manufactured by WACOM) And the initial photoelectric conversion efficiency was measured and found to be 6.7%. Thereafter, irradiation with pseudo-sunlight was continued, and the time until the photoelectric conversion efficiency was reduced to one-half of the initial value was measured as a half-time, which was 1,190 hours.

Example 7
Synthesis of Ligand 100 mL of tetrahydrofuran was added to 11 mL of a tetrahydrofuran solution of 2 mol / L lithium diisopropylamide and cooled to -70 ° C. While stirring the solution at −70 ° C., 2.0 g of 4-carboxy-4′-methyl-2,2′-bipyridine powder synthesized in the “ligand synthesis” step of Example 1 was slowly added. . Stirring was then continued for 1 hour at −10 ° C., and then 100 mL of a tetrahydrofuran solution containing 5.5 g of dodecyl bromide was added dropwise at −10 ° C. The reaction mixture was warmed to room temperature and stirred for another hour.

Thereafter, 250 mL of ice water was added, and the pH was adjusted to 2.0 with concentrated hydrochloric acid. The aqueous layer was extracted with ether, concentrated and dried, then purified by passing through a silica gel column, and the solvent was removed to obtain 1.1 g of product. This product was analyzed by ¹ H-NMR and found to be 4-carboxy-4′-tridecyl-2,2′-bipyridine.

Dye synthesis In Example 6, “Dye synthesis”, instead of 1.42 mmol of 4-carboxy-4′-methyl-2,2′-bipyridine, 4-carboxy-4′-tridecyl-synthesized above was used. The reaction was conducted in the same manner as in Example 6 except that 1.42 mmol of 2,2′-bipyridine was used, and 0.42 g of a product was obtained. ^When analyzed by ¹ H-NMR, it was found that this product was represented by the following formula (23). This product is referred to as “S2”.

Production of dye-sensitized solar cell, evaluation In "Production of dye-sensitized solar cell" in Example 6, except that the dye "S2" was used instead of the dye "S1", the same as in Example 6, A dye-sensitized solar cell was produced and evaluated in the same manner as in “Evaluation of dye-sensitized solar cell” in Example 6. The results are shown in Table 2.

Example 8
Synthesis of the ligand 30 g of 4,4′-dicarboxy-2,2′-bipyridine and 500 g of thionyl chloride were refluxed for 3 hours. After removing unreacted thionyl chloride, 500 mL of methylene chloride, 17 g of diethylamine and 1.5 g of 4-dimethylaminopyridine were added and stirring was continued at room temperature for 24 hours. The reaction mixture was then washed with dilute hydrochloric acid and purified by a silica gel column, and the solvent was removed to obtain 5.6 g of product. When this product was analyzed by ¹ H-NMR, it was found to be 4-carboxy-4′-N, N-diethylaminocarbonyl-2,2′-bipyridine.

Synthesis of Dye In “Synthesis of Dye” in Example 6, instead of 1.42 mmol of 4-carboxy-4′-methyl-2,2′-bipyridine, 4-carboxy-4′-N, synthesized above, The reaction was conducted in the same manner as in Example 6 except that 1.42 mmol of N-diethylaminocarbonyl-2,2′-bipyridine was used, and 0.31 g of a product was obtained. ^When analyzed by ¹ H-NMR, it was found that this product was represented by the following formula (24). This product is referred to as “S3”.

Production of dye-sensitized solar cell, evaluation In "Production of dye-sensitized solar cell" in Example 6, except that the dye "S3" was used instead of the dye "S1", the same as in Example 6, A dye-sensitized solar cell was produced and evaluated in the same manner as in “Evaluation of dye-sensitized solar cell” in Example 6. The results are shown in Table 2.

Example 9
Synthesis of Ligand In Example 8, “Synthesis of Ligand”, except that 46 g of N-methyldodecylamine was used instead of 17 g of diethylamine, Carried out in substantially the same way, 3.2 g of product was obtained. This product was analyzed by ¹ H-NMR and found to be 4-carboxy-4′-N-methyl-N-dodecylaminocarbonyl-2,2′-bipyridine.

Dye Synthesis In “Synthesis of Dye” in Example 6, instead of 1.42 mmol of 4-carboxy-4′-methyl-2,2′-bipyridine, 4-carboxy-4′-N— synthesized above was used. This was carried out in the same manner as in Example 5 except that 1.42 mmol of methyl-N-dodecylaminocarbonyl-2,2′-bipyridine was used, and 0.39 g of a product was obtained. Analysis by ¹ H-NMR revealed that this product was represented by the following formula (25). This product is referred to as “S4”.

Production of dye-sensitized solar cell, evaluation In "Production of dye-sensitized solar cell" in Example 6, except that the dye "S4" was used instead of the dye "S1", the same as in Example 6, A dye-sensitized solar cell was produced and evaluated in the same manner as in “Evaluation of dye-sensitized solar cell” in Example 6. The results are shown in Table 2.

Example 10
Synthesis of Dye In “Synthesis of Dye” in Example 5 above, instead of 39.08 mg of 4,4′-dicarboxy-2,2′-bipyridine, 4-carboxy-4′-methyl-2,2′- Except for using 34.28 mg of bipyridine (synthesized in “Synthesis of Ligand” in Example 5 above), the same procedure as in “Synthesis of Dye” in Example 5 was carried out to obtain 57 mg of product. It was. This was analyzed by ¹ H-NMR and found to be represented by the above formula (22).

¹ H-NMR (DMSO-d6, 298K, 270 MHz, δ (ppm)); δ = 9.41 (m, 1H),
9.06-8.70 (m, 5H), 8.27 (m, 1H,) 7.82-7.12 (m, 5H), 2.68 (s, 3H), 2.42 (s, 3H)

Production and evaluation of dye-sensitized solar cell The same procedure as in “Manufacturing and evaluation of dye-sensitized solar cell” in Example 5 was performed except that the above synthesized dye was used. Conversion efficiency was 5 The half-life was 945 hours.

Claims (6)

The pigment | dye represented by following formula (1).
ML ¹ L ² X ¹ X ² (1)
Here, M is a group 8 to 10 element on the long periodic table, and L ¹ and L ² are each independently a bidentate ligand represented by the following formulas (2) and (3): And X ¹ and X ² are each independently a monovalent atomic group or a monodentate ligand.

In the formula (2), A ¹ is a carboxyl group, a sulfonic acid group or a phosphoric acid group or a group corresponding to a salt thereof, R, R ¹ and R ² are each independently a monovalent organic group, and m1 and m2 each independently represent an integer of 0 to 3.

In the formula (3), A ² and A ³ are each independently a group corresponding to a carboxyl group, a sulfonic acid group or a phosphoric acid group or a salt thereof, and R ³ and R ⁴ are each independently a monovalent group. An organic group and m3 and m4 each independently represents an integer of 0 to 3. However, when both L ¹ and L ² are bidentate ligands represented by the formula (3), A ² and A ³ are not both a carboxyl group or a group corresponding to a salt thereof. . The dye according to claim 1, wherein in the formula (1), L ¹ and L ² are both bidentate ligands represented by the formula (2). The dye according to claim 1, wherein, in the formula (1), M is ruthenium. The dye according to claim 1, wherein, in the formula (2), R is an alkyl group having 1 to 50 carbon atoms or an alkylaminocarbonyl group having 3 to 50 carbon atoms. It is an object for dye-sensitized solar cells, The dye as described in any one of Claims 1-4. The dye-sensitized solar cell using the pigment | dye as described in any one of Claims 1-4.